Wing pulleys are utilized to support and/or drive endless conveyor belts for conveying materials from place to place. One example of a wing pulley is shown in U.S. Pat. No. 4,956,914 to Valster et al. Each of the wings of these wing pulleys have contact bars thereon for contacting the inside of the conveyor belt as it moves around the wing pulley. In the above mentioned patent, these contact bars are made of metal.
Under some circumstances, metal contact bars on wing pulleys will cause the conveyor belt to wear out prematurely. Consequently, softer lagging materials such as rubber have been devised, for example as shown in U.S. Pat. Nos. 3,363,476 to Brown; 3,392,594 to Van Gorp; 4,464,149 to Klyn and 4,836,361 to Harren.
When rubber or some other elastomeric material is used on the contact bar, it will obviously experience wear at a faster rate than if metal was used so this elastomeric lagging will need to be replaced on a fairly regular basis. Furthermore, it is sometimes desirable to change the composition of the contact surface to achieve an optimum result, such as moving to a softer elastomeric contact lagging if the conveyor belt is tending to wear out too quickly or, conversely, moving toward a harder elastomeric lagging if the lagging itself is wearing out too quickly.
It can also be appreciated by looking at the elastomeric or rubber lagging structures in the aforementioned patents that each invention uses a different structure for attaching the rubber or elastomeric lagging to each wing whereas a more universal system is desired so that by utilizing one structure, it could replace the lagging on a number of standard wing pulleys.
Such a standard replacement was conceived at one time and was referred to as a SUPERLAG lagging. This SUPERLAG replaceable lagging system used a polyelastomer extruded generally in the shape of the exterior portion of a standard contact bar for wing pulleys, but was made undersized so that it would stay onto a contact bar once it is slid over such contact bar by first sliding it on one end. A special tool was required to make this installation because of the tight fit required. One of the problems associated with this latter mentioned structure was that if the contact bar over which the SUPERLAG lagging was placed left any space between such lagging and the contact bar, flexing of this lagging would occur and this flexing or pulsating effect would cause the lagging to prematurely wear out. Consequently, while it would essentially achieve a desired amount of universality, this attempt to make it universal also made it susceptible to this flexing problem which led to premature failure.
Consequently, there is a need for a somewhat universal lagging system for wing pulleys which can be used on original equipment or can be used in a retrofit situation as an after market product. There is also a need for such a universal system which will not flex the elastomeric material unduly and therefore will not cause premature failure.